If coffee wouldn’t be such a challenge, we all wouldn’t be here.
Coffee has been around for many years but we are still struggling just to learn the basics about it. Consistent coffee roasting, grinding and brewing is quite a task and many aspects of the process are not properly understood and controlled. What we think we know today may be discarded tomorrow. That’s not a bad thing, however and the above remark by John Gordon summarized this very well. The joint discovery and sharing of knowledge brought together a group of fun and open minded baristas.
Think Coffee Out of Box
By Frans Goddijn & Jan van der Weel
(Frans’s version on kostverlorenvaart.blogspot.nl)
On 28 January 2016, the HQ of Sanremo in The Netherlands hosted a Barista Hustle. The evening, organized by Vincent Zwaan and Wouter Andeweg, featured international speakers: Maxwell Colonna-Dashwood, John Gordon, Ronny Billemon and Danillo Llopis.
Water and coffee brewing
Ronny Billemon of Pentair gave a talk about the effect of water on coffee flavour and machine health. In his presentation, he showed how water filtration can absorb unpleasant ingredients out of otherwise perfectly potable water. Brew water for coffee is best at pH values of 6.7–7.7, in a buffered balance between alkalinity and acidity. Chlorine (“an equipment killer”) needs to be absent from the brew water hitting our coffee grinds.
Not everything must be filtered out though. Too many minerals (“hard water”) can be harmful to the coffee machine but a certain amount of minerals is actually very helpful in dissolving the best compounds out of our coffee and creating a full bodied taste in the cup. So here as elsewhere in the world the “best” way is a compromise: enough minerals to extract good coffee, enough also to create a thin protective skin of sediment on the inside of boiler and pipes but not too many minerals because they clog up the machine, especially the finest tubes, and not too few because ultra low minerals numbers can create aggressive water that eats away at the metal in the machine, ruining both the machine and the coffee.
Generally you can say that water that is rich in minerals will give the cup more body. The downside however is that fewer of the fine aromas and flavours will come out.
The same beans can extract very differently with identical machines if the water used is very different, so it is always good to be aware of the local water quality. Ronny discussed a number of filtration methods:
- Resin filters that can be regenerated by salt (NaCl) are very effective in replacing Calcium ions with Natrium ions, but these Na-ions are less efficient in coffee extraction and the resulting coffee may be lacking in the full bodied taste that you aim for. This method may also lead to longer extraction times and increased bitterness.
- One could create pure H2O water by reverse osmosis and add the desired particles afterwards, but it is quite hard to mix a consistent and balanced water recipe this way.
- Then there are filters by BWT and the Claris Ultra which keep some calcium and magnesium in the brew water while limiting the carbonate values to safe levels for the machine. There is an optional bypass choice for low TDS which yields a fine spectrum of taste in a clear cup, or a higher TDS to get a more full bodied extraction. Magnesium, while being present in the water in much smaller amounts than Calcium, helps bring about the finer acidic notes in coffee.
A previous presentation by Ronny Billemon:
Understanding grinding to make a better grinder
Maxwell Colonna-Dashwood gave a very inspiring presentation about grinding. Grinding is problematic and not very well understood. Maxwell Colonna-Dashwood and his colleague John Gordon are developing a prototype for a new grinder that should give better and more consistent results than anything on the market at this moment. However, before building a new grinder prototype, one needs to understand the process of grinding better and to learn more, they have done extensive research.
A radically different angle
To illustrate the huge change of perspective that is necessary to improve our grinders, Maxwell showed a graph which Matt Perger frequently uses to show grinder performance.This graph shows the particle size produced by coffee grinders. One sees a tall “mountain” indicating the majority of particles have a bigger size, with a second much smaller “hill” indicating a smaller but significant amount of “fines”. Generally, the big elevation in the graph is considered to be the important one, the particles contributing to our coffee quality with the “fines” being a quantity we can do without.
The same data tells a radically different story though, if you display the surface area of the two groups of particles. Then all of a sudden, the “fines” are dominant since they jointly have a much greater surface area. What if these much finer particles yield much more coffee quality to the cup than the large particles?
Looking at the data this way also makes us think differently about the flow of water through the puck. Many baristas assume that too many “fines” sometimes clog up the puck, leading to an extraction that is too slow.
But what if it is the other way around?
Imagine a freeway with 7 lanes of fines. Water passes through without problem, but what if the traffic is jammed up with a few huge particles taking up 2 or 3 lanes each? Sure, some of the water will immerse the bigger particle and come out at the other end, rich with coffee solution, but most will have to travel around the obstacle, thus making the total room for water traffic more tight, and slow.
Maxwell also talked about the effect of temperature on grinding. In the morning, when the barista dials in his equipment and decides about the exact recipe, coffee seems to extract slower than later in the day. How can this be and how do we adjust to compensate, if we must?
This effect can be explained in two ways. First, temperature has an influence on the burrs and motor. Secondly and maybe more important: temperature has an influence on the breaking of the beans. Maxwell calls this the spaghetti principle. Uncooked hard spaghetti breaks easier at lower temperature, when it is more brittle. The very same effect can be seen in coffee grinding. Colder coffee beans tend to break more easily and cooler coffee grinds can have twice the amount of fines. This has a big influence on extraction. So, even if we compensate by grinding finer, we have changed the temperature and thus we have accidentally changed our recipe for the day.
Timed grinders cannot dose consistently because this effect. Quick successive grinding in a busy cafe heats up the grinder body and this will lead to a coffee dose that will gradually increase up to 0.2g or a little more (we can conform this, as we have observed this during our review of the Compak E8 grinder for KTC magazine [Jan & Frans]).
The Mythos Clima Pro grinder attempts to regulate this temperature influence. The dosing of this grinder should be more consistent. The grinder does this by a combination of heating up and cooling down. The temperature of this grinder is however much higher than any other grinder on the market today and the question remains if this has a positive effect on cup quality.
Motor speed. Temperature is not the only factor to influence coffee grind quality. Motor speed has a big influence as well on extraction and cup quality. Lowering the RPM of a coffee grinder can have a big influence on extraction yield and extraction time. In one test Maxwell and his team decreased the RPM and got a much shorter shot (18s vs 25s) that yielded much higher (19% vs 18%). This effect can be explained by the effect grinding speed has on the particle sizes and shapes. Another issue with grinders is that the RPM is often not stable. A higher operating temperature can cause the RPM to fluctuate. For more consistency we need a more consistent RPM. When single dosing, it is advised to have the motor running when throwing in the dose, so the burrs are already on full speed and won’t be starting up with their jaws full of beans.
Boulders and fines
For clarity, Maxwell calls the larger coffee particles out of the grinder boulders. The small coffee particles are generally called fines. Maxwell explains that boulders and fines are not the same particles but just different in size. When you separate boulders from fines and extract them separately, you will end up with a very different cup. One explanation for the popularity of the EK43 grinder could be that it seems to be better in smashing boulders.
Maxwell and John also investigated different ways of grinding. Next to conical, flat burr and roller grinders there is a very interesting way of grinding that is being used in the production of medicines. This method is called air grinding, with a powerful vortex breaking up the material in neat particles. This very expensive method leads to much better particle control. In the near future, Maxwell and John will be allowed to borrow one of those to investigate what it can do to roasted coffee beans.The prototype is still under development and Maxwell and John currently have no contract with a manufacturer. Their prototype does have some specifications to be revealed though:
- The basic idea of this grinder is it will give more consistency and control. Furthermore the idea is that it will be the only grinder that you will need
- The design will prevent a buildup of heat in the grinder
- The RPM can be tightly controlled
- The design uses a self weighing predosing system
- It will be a one stop grinding solution. It can grind for all brew methods. The grinder will have multiple hoppers to work with different coffees
- The grinder can consistently predose and blend coffees itself
John pointed out that a better grinder can result in more time for the customer. Customer service and friendliness is often horrible in coffee bars. That’s something that should change and if the equipment needs less attention from the barista, the customer can receive more “love and care”.
Coffee extraction: Think out of the Box
John gave a short talk about coffee extraction. Many know the Brewing Control Chart as used, for instance, by the VST CoffeeTools app. The theory behind it indicates that coffee tastes best at 18-22% extraction. John invites people to challenge this idea:
“We all should start thinking outside this box. Some coffees can taste great at 14% even.”
One other big advantage in trying out extractions to be in all corners outside “the box” is that this gets you acquainted with the taste of all these variations of extraction. Then, if you get lost, you will be able to taste the extraction and recognize where you are on the chart. It will be easier to get where you want to be, even if that is on another spot outside “the box”.
At the conclusion of the evening, Wouter Andeweg won a Sanremo Zoe single group machine during a latte art throwdown. Kuba Snikker made second, earning a Sanremo Opera branded Gorilla Tamper (picture by Sanremo):